The lines ending with "doesn't contain a vlid partition table" shouldn't (obviously) be there. They come from stderr of "fdisk -l".

I corrected the problem by redirecting stderr of fdisk -l to /dev/null in line 1018 of src/common/libmondo-tools.c (see attached patch)

For a bit more of discussion: actually I get the same output from cron nightly backups, but this way to demonstrate it seemed simpler. Also, it seems that older versions of fdisk used to skip lvm volumes when doing an fdisk -l, but not the version in ubuntu 12.04.